Lens block



May 15, 1923. 1,4553138 H. w. HILL.

LENS BLOCK I Filed Nov. 25. 1920 INVENTOR HA RR Y w. H/LL I ATTnRNEYsPatented May is, 1923.

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HARRY W. HILL, OF SOUTHBEIDGE,MASSACHUSETTS, ASSIGNOR IO AMERICAN"OPTICAL COMPANY, OF SOUIHBBIDGE, MASSACHUSETTS, A. VOLUNTARY ASSOCIATIONOF LEASSAC HUSETTS.

LENS BLOCK.

Application. filed November 23, 1920. Serial No. 426,005. i

To all whom it may concern:

Be it known that I, HARRY W. HILna citizen of the United States,residing at.

Southbridge, in the county of Worcester and State of Massachusetts, haveinvented certain new and useful Improvements in Lens Blocks, of whichthe following is a specification.

This invention relatesto a lens block and has for its leading object theprovision of a device which shall serve to satisfactorily mechanicallyhold large lens blanks or discs such as are most commonly used in theman ufacture or production of bifocal lenses, but which are capable ofvarious other uses.

A further object of the present invention is the provision of a noveland improved any undue lateral pressure or the like tend- I mechanismfor mechanically securing lenses in holders for the grinding operation,which shall securely and satisfactorily hold and retain the lens, butwhich will not subject it. to

ing to spring or twist the material of the blank.

A further object of the invention is the provision of a device of thischaracter in which the parts shall be so related that accidentalrelative twisting of the lens and body of the holder will be prevented.

Other objects and advantages of the improvement include the provision ofa holder which shall automatically position or center the work, whichwill permit of the removal and replacement of the lens on the block asdesired and insure the lens being in proper position for continuance ofthe grind the various difliculties experienced in connection with theuse of pitch or other adhesive for grinding such lenses.

Figure Iis a plan view of a blocked lens in position for grinding.

Figure II is a transverse sectional view illustrating the grindingmember in use in connection withthe improved mechanism.

Figure III is a sectional view similar to Figure II showing a slightlydifferent shape of backing member.

Figure IV is a bottom view with the looking collar removed.

The body portion 1 of the lens block has a face 2 substantiallycorresponding to the curve on the rear face of the lens blank 8 toprovide a seat. for the lens blank. If de sired, as shown in Figure III,the seat may be curved on a trifle shorter radius than that of the glassso itwill contact with the glass at the edge portion rather than center.This is important. due to the fact that as is well known, glass is abendable material, lateral strains as by clamping tending to spring thematerial or distort its surface. In this invention, therefore, in placeof making use of lateral clamps on the discs here in question the glassdiscs 4 with the flaring bevelled.

edges or sides 5 are formed, while to engage these sides anannulus 6having an inclinedface 7 is employed for sliding slightly down over theedge 5 of the glass blank. Thisannulus 6 has a depending collar 7slidable on the lens block 1 and exteriorlythreaded to engage with thethreaded flange 8 of the clamp ring 9. In use the lens blank is pl cedon the block 1 and the annulus 6 slipped down thereover, automaticallyand accurately centering the blankand properly position ing it on theholder 1, after which the clamp ring 9 is turned to draw theannulus 6down toward the member 1, clampingly engaging with a downward pressurethe bevelled or inclined edge 5 of the glass blank and secure lypressing it against the member 1 so it will be properly supported.

The member 1 may either-exactly fit the lens or it may be of such shapeas to engage the lens just under the edge toward the clamping point ofthe annulus 6. In either event it has been found that no distortionofthe glass takes place with this form of the invention, the test to whichit is put for this purpose being the Newton ring test, and it beingfound that if the blank be tested on the Newton ring principle, whenclamped in position in the holder and the holder then released, it willstill test the same showing there is no distortion due to the clampingaction.

There is one other point that must be considered, and that is to preventrelative twisting of the parts. This is accomplished by forming thegroove or key-way 10 in the annulus 6 to receive/the pin or key 11 onthe body portion, so that when the annulus is placed over the bodyportion and lens it will immediately ,slip down onto the lens, the pin11 being received. in the slot 10 and 1nterlocking with the wallsthereof, locking these parts against any possible twisting.

It is also to be noted that the glass blanks 4c is so constructed thatthe annulus 6 will slip down. a certain distance: thereover, leaving theupper surface projecting above the annulus so that the grinding toolwillride up freely over the side of the tool without coming into contacttherewith. 7

It is to be noted that the body portion 1 is centrally provided with asocket 12 to receive a rotatable grinding spindle, in use the blockbeing rotated about the dotted line shown in Figure II as an axis, whichmay be termed the axis of grinding. It is the purpose of the inventionto clampingly secure the lens bypressure applied in the direction ofthis axis of grinding rather than opposed to this axis, thereforereducing the the grindin liability oi springing of the glass duringwhile permitting of its being positively securely held.

lVhat is claimed is: i 1. A lens block comprising a lens supportingmember having a seat to'receive the lens slightly more concave centrallythan the curve of, the lens to be mounted thereon, a lens engagingannulus slidably but nonrotatably carried by the seat and projectingthereabove, and a clamp ring interlocking with the annulus and having aportion engaging the opposite face of the lens supporting member forclampingly drawing the annulus in the direction of the lens seat.

2, A lens block comprising a body. portion having a lens receiving seatformed on one side and a clamp ring receiving groove formed on theopposite side, an annulus telescopically fitting the body portion of thelens block and having a depending threaded collar portion and aninwardly extending bevelled lens edge engaging portion, and a clamp ringhaving a portion seated in the groove of the body portion of the lensblock and having a portion ininterlocking threaded engagement with thedepending portion of the lens clamping annulus. I

3. A lens block comprising a body portion having a lens receiving seatformed on one s1de and a clamp ring reciving groove formed on'theopposite side, an. annulus telescopically fitting the body portion ofthe lens block and having a depending threaded collar portion and aninwardly extending bevelled lens edge engaging portion, a clamp ringhaving a portion seated in the groove of the body portionofthe lensblock and havingz'i portion in interlocking threaded engagement with thedepending portion of the lens clamping annulus, and means for holdingthe lens clamping annulus against A rotation relative to the block.

having a portion in interlocking threaded engagement with the dependingportion of the lens clamping annulus, the body portion of the lens blockhaving a cut away portion peripherally of the lens engaging side intowhich the inwardly projecting portion of the clamping annulus isreceived as the parts are tightened.

In testimony whereof l have afiixed my signature, in presence oftwowitnesses.

' HARRY HILL, l/Vitnesses: x

ALICE Gr. I-IASKELL, ESTHER M. LAFLER',

